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A conversation with the new head of civil engineering

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Joe Labuz

Earlier this year Professor Joe Labuz accepted a five-year appointment as head of the Department of Civil Engineering. Labuz served as interim department head since July 2012 and as a member of the faculty since 1987. He has conducted more than 20 transportation-related research projects in the areas of pavements, soils, and structures and has also served students as the director of both undergraduate and graduate studies. Below he shares his vision and directions for the department.

Vision

I am very much looking forward to my tenure for a number of reasons: the faculty are among the world leaders in their fields; our students more than ever are focused on developing skills that can be used to serve society; and the college is committed to supporting and rewarding cutting-edge research and quality instruction.

I should first acknowledge the previous head, Professor Roberto Ballarini. Through his leadership, the department experienced growth in research expenditures and student satisfaction. His vision was one of excellence in all that we do.

I will try to continue his legacy of excellence, while striving for my vision of building—building progressive educational programs in civil engineering, environmental engineering, and geoengineering; building research thrusts that are aligned with regional and state priorities; and building a vibrant, cohesive department where faculty and students are recognized nationally and internationally for distinguished academic achievement.

Priorities

One of my first priorities is to build a state-of-the-art measurements laboratory for hands-on learning and instruction. Just as numerical modeling has become a common thread of engineering analysis and design, so too should sensing be a component of our core programs.

New degree program

Furthermore, the department is proposing a new degree program, the first in Minnesota: bachelor of environmental engineering (BEnvE). This reflects the extensive interests of our faculty and students in forwarding environmental issues within a civil and geoengineering paradigm. Our interests span from clean energy to water treatment, from hazardous waste to groundwater remediation, to name a few. The introduction of this program aligns us with many other leading civil engineering departments nationwide.

Name change

Perhaps the most exciting news is the name change to Department of Civil, Environmental, and Geo- Engineering. The proposed name will better reflect the character of the department and readily identify our degree programs. Note that the name will be unique in the U.S. The name change, when approved by the Regents, will be official on July 1, 2014.

Research

On the research side, several initiatives are focused on issues important to the region and nation. Measurement and analysis of transportation infrastructure, environmental restoration of lakes and streams, and renewable energy such as wind and biofuels have substantial funding in the department, and resources such as faculty hires and laboratory space are being dedicated to these thrust areas.

CE building and labs

Finally, the building itself is being renovated and some laboratories are being remodeled, as is the second floor student lounge, through the generous support of WSB & Associates and the College of Science & Engineering. The unique underground structure received the 1983 outstanding civil engineering achievement award from ASCE. I look forward to inviting the community to visit sometime in December 2013 to celebrate the 30-year anniversary.

CTS fall research seminars begin September 26

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This fall, CTS will offer five research seminars on transportation topics ranging from resilient communities to asphalt at low temperatures.

Seminars will be held every Thursday from September 26 through October 31 (except Oct. 17) on the U of M campus in Minneapolis. You can either attend in person or watch the live webcast of each seminar. Additional information is available on the CTS website.

Seminar schedule:

Rebuilding stronger, less expensive roads with recycled asphalt

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While the eco-friendly mantra "reduce and reuse" has been around for decades, its role in asphalt pavement rehabilitation has been discovered much more recently. In years past, when an asphalt road began to deteriorate, the answer was either to apply a hot-mix asphalt overlay to the road's surface or perform a complete reconstruction of the pavement.

"The problem is that other options should be considered," says University of Minnesota civil engineering professor Joseph Labuz. "Fully reconstructing a road is expensive and time consuming, and though the overlay method is fast and less expensive, it doesn't always provide a lasting solution because previous distresses and cracks eventually make their way up to the new layer of pavement."

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As an alternative to these two methods, in-place asphalt recycling continues to gain popularity. Full-depth reclamation (FDR) is a pavement recycling technique in which the existing pavement and some of the existing base layer are broken up and blended to form an improved base for a new asphalt surface. Sometimes an additive is mixed in with the recycled pavement layer to further increase its stability, which is known as stabilized full-depth reclamation (SFDR).

As FDR and SFDR gain popularity, highway engineers need ways to effectively evaluate their properties and correctly apply pavement design guidelines. Few documented field studies have measured material performance, however, so assigning the proper design values to FDR and SFDR pavements is done conservatively.

To provide engineers with more guidance, the Minnesota Department of Transportation (MnDOT) sponsored a U of M study to estimate the proper design values and assess the effects of seasonal temperature changes on these pavements.

"MnDOT uses granular equivalency (GE) to describe stiffness of asphalt and base materials," says Shongtao Dai, research operations engineer with MnDOT's Office of Materials and Road Research. When this project was initiated in 2009, there was no well-defined method to determine GE, he explains, and MnDOT recommended a GE of 1.0 (equivalent to a "class 5" aggregate).

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Over three years, the U of M research team led by Labuz evaluated tests performed by MnDOT to determine the stiffness of seven sections of FDR and SFDR county roads in Minnesota. During the spring thaw of each year, tests were conducted daily during the first week of thawing to document seasonal weakening of the pavement's base layer. After the spring thaw period, tests were conducted monthly at each location to capture the pavement strength changes throughout the season.

The study results demonstrate the benefits of SFDR pavements in particular: SFDR pavements were determined to have a higher "stiffness rating" than had previously been assigned by MnDOT, and GE was estimated at about 1.5—meaning less expensive aggregates could beconsidered. In addition, while both pavement types exhibited the seasonal effects typical for asphalt pavements—lower stiffness in the spring than in the summer and fall—most of the SFDR pavements showed improved seasonal stiffness.

"The research has provided guidance and confidence to MnDOT on determining GE values for SFDR materials," Dai says.

Brian Noetzelman, county engineer of Pope County and a member of the project advisory panel, adds that if the GE for SFDR rose from 1.0 to 1.5, it would give 50 percent more carrying capacity to the existing base GE at a minimal cost. "Current 9-ton designs could now be 10-ton designs with the same design structure. What a tremendous savings for counties!"

Reprinted from CTS Catalyst, June 2013.

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Center for Transportation Studies

University of Minnesota

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Phone: 612-626-1077

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E-mail: cts@umn.edu

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